<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="app">
        <div v-if="flag">老付</div>
        <button @click="flag=!flag">click me</button>
    </div>
</body>
<script src="./js/vue.js"></script>
<script>
    Vue.config.productionTip = false;

    var vm = new Vue({
        el:"#app",
        data:{
            flag:true
        }
    })
</script>
</html>